Patent Literature 1 discloses a touch sensor system for detecting a distribution of values of a plurality of electrostatic capacitances formed at intersections of a plurality of first signal lines and a plurality of second signal lines. A conventional touch sensor system for detecting a distribution of electrostatic capacitance values attempts to recognize, by signal processing, a finger and hand part with which a touch panel is being touched (see Patent Literature 2).
FIG. 12 is a block diagram illustrating a configuration of a conventional touch sensor system 91 disclosed in Patent Literature 3. The touch sensor system 91 includes a touch panel 93 and an electrostatic capacitance value distribution detecting circuit 92. The touch panel 93 includes drive lines HL1 through HLn arranged parallel to each other in a horizontal direction, sense lines VL1 through VLm arranged parallel to each other in a vertical direction, and a plurality of electrostatic capacitances formed at intersections of the drive lines HL1 through HLn and the sense lines VL1 through VLm.
The electrostatic capacitance value distribution detecting circuit 92 includes a driver 95. The driver 95 drives the plurality of electrostatic capacitances by a voltage application to the drive lines HL1 through HLn in accordance with a code sequence. The electrostatic capacitance value distribution detecting circuit 92 includes a sense amplifier 96. The sense amplifier 96 reads out, via the sense lines VL1 through VLm, a linear sum of voltages corresponding to the respective plurality of electrostatic capacitances driven by the driver 95, and then supplies the linear sum of voltages to an AD converter 98. The AD converter 98 subjects, to AD conversion, the linear sum of the voltages which has been read out via the sense lines VL1 through VLm, the voltages corresponding to the respective plurality of electrostatic capacitances, and then supplies, to a capacitance distribution calculating section 99, the linear sum of the voltages which has been subjected to the AD conversion.
The capacitance distribution calculating section 99 calculates an electrostatic capacitance distribution on the touch panel 93 in accordance with the code sequence and the linear sum of the voltages which has been supplied from the AD converter 98, the voltages corresponding to the respective plurality of electrostatic capacitances, and then supplies the electrostatic capacitance distribution thus calculated to a touch recognizing section 90. The touch recognizing section 90 recognizes, in accordance with the capacitance distribution thus supplied from the capacitance distribution calculating section 99, a location on the touch panel 93 at which location the touch panel 93 was touched.
The electrostatic capacitance value distribution detecting circuit 92 includes a timing generator 97. The timing generator 97 generates (i) a signal which specifies operation of the driver 95, (ii) a signal which specifies operation of the sense amplifier 96, and (iii) a signal which specifies operation of the AD converter 98, and then supplies the signals (i) through (iii) to the driver 95, the sense amplifier 96, and the AD converter 98, respectively.
Patent Literature 4 discloses an arrangement in which (i) a hand placing region indicative of a region in which a hand is placed so as to carry out a pen input with respect to a touch panel which includes a plurality of electrostatic capacitances provided in a matrix pattern is defined by application software that is installed in a host device connected to the touch sensor system, (ii) a frame defining the hand placing region is drawn, and (iii) a position of the hand placing region is corrected at any time following a movement of the hand placed so as to carry out the pen input with respect to the touch panel.
Patent Literature 5 discloses an arrangement in which (i) a hand placing region indicative of a region in which a hand is placed so as to carry out a pen input with respect to a touch panel which includes a plurality of electrostatic capacitances provided in a matrix pattern is detected in accordance with a strength of an electrostatic capacitance signal indicative of a change in electrostatic capacitance and (ii) a value of an electrostatic capacitance signal which value corresponds to an electrostatic capacitance provided in the hand placing region thus detected is replaced by a non-value indicative of a state in which no touch input is carried out.